What a Junior ADU & Interior Conversion Actually Costs and Takes in Villas, FL
A junior ADU and interior conversion in Villas, FL typically runs $50,000 to $130,000 when you convert an attached garage, an underused bonus room, or a portion of an existing home into a self-contained living unit with its own kitchenette, bathroom, and private entrance. Most jobs take 12 to 20 weeks from the day we start framing to final Lee County inspection. Call (844) 638-7249 to schedule a free on-site estimate and get a written, line-by-line price on your specific Villas property.
How We Actually Build a Junior ADU in an Existing Home
Every junior ADU and interior conversion follows the same physical sequence, but no two Villas homes are identical. We walk you through every stage before we start so you know exactly what to expect and when you’ll need to make decisions. Here’s the process we’ve refined over more than 42 years of residential construction.
Stage 1: Site walk and as-built documentation (Days 1-3). We’re not the contractor who hands you a ballpark number over the phone. We measure the existing space, check slab flatness, trace plumbing and electrical runs, and document ceiling height, window locations, and structural walls. On a pre-1985 Villas CBS ranch, we also inspect for corroded rebar and deteriorated mortar joints - issues we see regularly in this housing stock and that need to be addressed before any interior work begins. You get a fixed-price proposal, not an estimate that creeps.
Stage 2: Permitting and Lee County compliance (Weeks 1-3). Any junior ADU in unincorporated Lee County triggers a building permit, an electrical permit, and a plumbing permit at minimum. If your home was built before 2002 and the conversion involves exterior wall penetrations or changes to the existing structure, the Lee County Building Department will often require a hurricane-strap retrofit inspection and possibly a FEMA elevation certificate review before they’ll issue the permit. We pull every permit, coordinate inspections, and handle the paperwork. This stage is the one that surprises Villas homeowners who haven’t done a major project since Hurricane Ian, and it’s why you want a contractor who’s already navigated the post-Ian compliance landscape here.
Stage 3: Demolition, structural rough-in, and moisture mitigation (Weeks 2-5). We gut the conversion area to studs and slab, remove any non-load-bearing walls that don’t fit the floor plan, and deal with what we find. Given Villas’s 60-plus-inch annual rainfall, a water table often within 18 inches of grade, and persistent post-Ian soil saturation, we pay obsessive attention to slab moisture and existing drainage. We install a vapor barrier where needed, address any slab cracks with epoxy injection, and rough in new plumbing, electrical subpanels, and HVAC ducting. At this stage, you’ll confirm exact kitchenette and bathroom fixture locations so our rough-in is dead-on.
Stage 4: Wall close-up, finishes, and systems (Weeks 4-16). Insulation, drywall, flooring, trim, painting, cabinet and countertop installation, fixture trim-out, and appliance hookup happen in sequence. You’ve already chosen your finishes back in Stage 1, so there’s no scrambling. We install the separate HVAC mini-split or tie into the existing system depending on what the Manual J load calculation tells us. The kitchenette gets its own GFCI-protected circuits per NEC. The bathroom exhaust fan vents to the exterior, never into an attic, which is a common corner-cutting shortcut we fix on Villas homes constantly.
Stage 5: Final inspections and punch list (Weeks 16-20). Lee County inspects framing, electrical, plumbing, mechanical, and final building. We walk the unit with you, note anything that needs attention, and resolve every item on the punch list. Your 730-Day Done Right Promise starts the day we hand you the keys. If anything isn’t right, we make it right.
The Choices That Shape Your Junior ADU
You’re not picking from a limited menu of builder-grade bundles. Every surface and system gets specified to match how you’ll actually use the space, whether it’s for an aging parent, a long-term rental, or a college kid home for summers. These are the decisions that matter most.
- Kitchenette configuration. Compact doesn’t mean compromised. You choose between an under-counter refrigerator and freezer drawer setup or a full-height apartment fridge, a two-burner induction or electric cooktop (gas requires additional venting and a Lee County gas permit), and cabinet lines from KraftMaid that let you match the main home’s look or go entirely custom. Countertops run from solid surface to quartz; we fabricate locally to your exact template.
- Bathroom scope. A three-quarter bath with a walk-in shower, toilet, and vanity is the standard junior ADU layout. If you have the square footage, a full tub-shower combo adds resale appeal. We install Kohler fixtures as standard, with upgrades to thermostatic shower valves and comfort-height toilets that make the unit accessible without looking institutional.
- Flooring and moisture handling. This is a Villas-specific decision and we don’t let it slide. LVP and tile outperform laminate and engineered wood in our humidity and slab-moisture conditions. We recommend a 20-mil wear-layer LVP or porcelain tile on a crack-isolation membrane over the slab. Carpet in a ground-floor ADU here is a mold risk we’ll talk you out of.
- Private entrance and security separation. If the conversion shares a wall with the main house, we build a fire-rated separation assembly and install a solid-core entry door with its own deadbolt. You decide whether the ADU gets its own address-marked entrance off a side yard or connects through a shared interior corridor with a locking door. Post-Ian code requires impact-rated exterior doors if the opening faces an exposure that wasn’t previously rated.
- Climate control independence. A ductless mini-split gives the tenant or occupant full temperature control and is the most energy-efficient option. Tying into the main home’s central system is cheaper upfront but creates disputes over thermostat settings and may not pass a Manual J load review. We’ll run both numbers and show you the payback.
What a Junior ADU & Interior Conversion Costs in Villas, FL
A junior ADU and interior conversion in Villas lands between $50,000 and $130,000. The spread is wide because the final number depends on what you’re starting with and what you want to end up with. Here’s what pushes a project toward one end of that range.
Square footage of the converted area. A 250-square-foot bedroom-and-bath conversion lands in the lower third. A 600-square-foot garage conversion with a full kitchenette, separate HVAC, and a private entrance pushes toward the upper third.
Condition of the existing slab and structure. If we open walls and find corroded rebar, deteriorated CBS mortar joints, or slab cracks that need epoxy injection and a moisture barrier, structural remediation adds $3,000 to $12,000 before we hang a single sheet of drywall. This is not rare in 1960s-1980s Villas homes; it’s what we expect.
Plumbing and electrical scope. Adding a bathroom where no drain line exists means cutting the slab and running new waste pipe to the existing sewer lateral. That’s $4,000 to $9,000 depending on distance and depth. A new electrical subpanel dedicated to the ADU adds $1,500 to $3,500.
Finish level. Builder-grade cabinets, laminate countertops, and a fiberglass shower base keep material costs down. Custom KraftMaid cabinetry, quartz counters, floor-to-ceiling tile, and a ductless mini-split push the total up by $10,000 to $25,000. You choose where to spend.
Permit and compliance costs. Lee County permit fees, plan review, and required third-party inspections run $2,500 to $6,000 on a junior ADU. If the project triggers a hurricane-strap retrofit, an electrical panel upgrade to meet current code, or a FEMA elevation certificate review, those costs are separate and we itemize them in your proposal. Our written estimates include every permit fee and inspection cost we know about upfront. No change orders because we “didn’t see it coming.”
Every estimate we write is a fixed-price, line-item document. Call (844) 638-7249 to get one for your Villas home.
What Villas, FL Homes Specifically Do to a Junior ADU Conversion
Villas sits on the inland side of the Caloosahatchee River estuary in unincorporated Lee County, squarely in the path Hurricane Ian took in September 2022. That changed everything about how building permits get issued here and what a contractor finds when they open walls on a pre-2002 CBS ranch. We’ve done enough junior ADU conversions in this exact housing stock to know what’s coming.
The homes we work on in Villas are almost entirely slab-on-grade concrete block ranches built between about 1960 and 1985, long before Florida’s post-Andrew high-velocity hurricane zone codes took effect. Most lack modern hurricane straps, impact-rated openings, and code-compliant roof-to-wall connections. When we pull a permit for an interior conversion that modifies exterior walls or electrical service, the Lee County Building Department routinely requires a strap-retrofit inspection and may demand a flood vent installation or elevation certificate review based on the post-Ian FEMA advisory flood maps. That’s not a hassle. That’s the law, and we handle it start to finish.
The other thing Villas gives us is moisture. Sixty-plus inches of rain a year, a water table that sits within 18 inches of the slab, and two post-Ian wet seasons that saturated the soil mean we treat every slab as a potential moisture source. We test. We install vapor barriers. We recommend finishes that don’t warp or mold. These aren’t best practices we read about; they’re what keeps a junior ADU in Villas dry and durable ten years after we leave.
If you’re considering a junior ADU as part of a larger reconfiguration of your home, you may also want to look at our Home Additions & ADU in Villas services. Many homeowners pair a junior ADU with Kitchen Design & Layout in Villas or Small & Partial Kitchen Remodels in Villas to update the main house while they’re already opened up. Our Home Additions & ADU crew handles the full scope. We cover every neighborhood in Villas.
Serving Villas, FL - Our Local Coverage Area
We’re based in the Villas area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions About Junior ADU & Interior Conversions in Villas
Plan on 12 to 20 weeks from the day framing begins. Permitting adds 2 to 4 weeks on the front end, depending on Lee County review backlog and whether a hurricane-strap retrofit or elevation certificate review is triggered. We include the full permitting timeline in your project schedule at the estimate stage.
Yes. Any conversion that adds a bathroom, kitchenette, or sleeping area in unincorporated Lee County requires building, electrical, and plumbing permits at minimum. If the work touches exterior walls or the electrical service, additional structural and FEMA-related reviews often apply. We pull every required permit and pass every inspection. An unpermitted ADU in Villas becomes a liability when you sell, insure, or rent the property.
Sometimes. If the conversion area is adjacent to an existing bathroom and you can share a wet wall, plumbing costs drop significantly. Structural walls only get touched if the floor plan demands it. We design around what’s there when we can, but we won’t compromise a functional layout just to save a few thousand dollars on slab cutting. We’ll show you both options and let you decide.
Our fixed-price estimate includes all labor, materials, permits, inspections, finish carpentry, painting, flooring, fixtures, and appliance installation. It does not include the appliances themselves, window treatments, or furniture. We itemize everything. The price you see is the price you pay, backed by our 730-Day Done Right Promise.
Every junior ADU and interior conversion we build is covered by the Groundwork Construction Co. 730-Day Done Right Promise. If something isn’t right, we make it right. That’s one of the longest workmanship guarantees in residential construction, and we put it in writing because we’ve been doing this long enough to know the work holds up. Manufacturer warranties on materials, fixtures, and appliances are separate and we pass every registration and warranty card to you at project close.
Get a Fixed-Price Estimate for Your Junior ADU in Villas
A junior ADU and interior conversion is a significant investment, and you deserve a real number before you commit. Call (844) 638-7249 to schedule a free on-site estimate. We’ll walk your Villas property, document the existing conditions, talk through your options, and hand you a written, line-by-line proposal. No ballpark guesses. No change-order surprises. Just upfront pricing from a contractor who’s been doing this work for over 42 years.
Written by Derek Hollenbeck, Owner at Groundwork Construction Co., serving Florida homeowners since 2014.